Sim locked randomly

i woke up one morning and i checked the time on my iPhone 8 that operates ios 12.4, which is the latest update to date, I noticed “sim locked” on the top left corner of the screen when I turned my phone on to check the time... And i didn’t do anything to my sim pin that night before... any idea how this could’ve happened? I’ll make this clear again I did not mess with my sim pin the night before!

super weird. Please help me